On Presidents Day 2021 (likely at Midnight between Sunday and Monday), in a move that was entirely foreseen and entirely understandable (unlike with the UP cab signals), BNSF will retire the Santa Fe era IIATS Automatic Train Stop system that was popular during the first wave of technical railway safety aids in the 1920's and 30's.
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| Bi-directional ATS shoes under a classic ATSF signal bridge on the Marceline Sub. |
The inductive system, similar to the magnetic Automatic Warning System in UK service, was identifiable by the upside-down canoe shaped shoes mounted to the right of the track. When activated by a signal displaying an indication other than Clear, the shoes would trigger a warning horn in the cab and failure to acknowledge would result in a penalty brake application. Set as the most basic requirement by ICC directive for travel 80mph and over after 1948, railroads couldn't abide by its modest cost, resulting in an unofficial nation-wide rail speed limit. While the Southern, New York Central and Santa Fe maintained hundreds of ATS equipped route miles, all but the ATSF managed to abandon their systems around 1970 with the general collapse of passenger services. For whatever reason, the ATSF Chicago to LA "Super Chief" route retained its ATS system, allowing the successor Amtrak Southwest Chief to travel for long distances at speeds up to 90mph.
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| Inert "always on" ATS shoes protecting a permanent speed restriction on the Marceline Sub |
A clever system that could fail safe with just inert steel components, IIATS was in service on the Marceline Sub across Missouri and the Needles, Seligman and Gallup Subs between Barstow and Dalies, allowing for speeds of up to 90mph on Class 5 track. Unfortunately the system relied on careful clearances between the lineside shoes and the pickup coils, that were mounted, as needed, only on the head end locomotives on freights traveling this territory. Moreover, BNSF went out of its way never to expand the system from what they had inherited, therefore as tracks were upgraded to bi-directional operation, the ATS would remain in the old single direction ABS configuration. In other cases ATS was only in service in one direction on both tracks.
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| ATS shoes for westward movements only on both tracks on the Seligman Sub. |
The good news is that active PTC is being accepted by the FRA as a valid ATS replacement. Moreover, in the affected areas since signaling, track and grade crossings are all configured for 90mph, speeds will either remain at 90mph or will be raised to 90mph where ATS did not cover specific directions of travel. It remains unclear if previously non-ATS territory that is equipped with Class 5 (90mph pass, 70mph freight) track, will see similar speed increases. I have been informed that, similar to the METRA ATS shoes, the timetable for removal is 90-180 days. However the BNSF ATS territory is probably 10+ times the total route territory, so we'll see.
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| Railrunner territory semaphore with ATS shoe on the Glorieta Sub. |
Due to absent or incomplete PTC, ATS will remain on parts of the Glorieta (controlled by New Mexio Railrunner), Raton, LaJunta and Topeka Subs, however it has been all or partly suspended on most of this territory since the early 2000's, lowering speeds to 80mph where applicable. Due to the nature of how ATS works, I have been told that Amtrak Train 3 and 4 run with the system on, but do not report any activation issues.
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| ATS shoe on the NJT RiverLINE. The only instance where IIATS is used as a trip stop. |
In addition to the Chief route, ATS will remain in service, enabling 90mph on the former ATSF San Diego route, now playing host to Amtrak Surfliner Trains as well as on the NJT RiverLINE where the technology is used, shockingly, to enforce positive stops at absolute signals. Anyway, get your photos (or after 2/15 get your ATS shoes) quickly because after President's Day, they could start to vanish without warning.
The Amtrak notice on this subject stated that the wayside equipment will be removed between 90 and 180 days after the removal from service on 2/15.
ReplyDeleteI grew up in ATS territory along the Chicago & North Western in suburban Chicago. The C&NW's ATS was from General Railway Signal, as was most of their signaling equipment. Paradoxically, the C&NW's ATS in Chicago suburban territory was installed during the late Sixties.
The Santa Fe was a Union Switch & Signal loyalist, so most of their ATS is that company's variant.
Among the flaws of intermittent inductive ATS (IIATS) is the only thing it does is enforce that the engineer acknowledge a signal less favorable than Proceed. The engineer can sail past a restrictive signal without heeding its indication.
Another shortcoming of IIATS is that the system is not fail-safe in that one of the inductors could go missing. Its absence would be undetected by the signal system unless a human happened to observe it.
During my last trip to Chicago shortly before COVID-19 arrived, I noticed that the Union Pacific ATS shoes on the ex-C&NW had already been removed after their decommissioning last fall.
I suspect the removal consisted of little more than disconnecting the inductor wires at the case, and torching off the ATS shoe at trackside; there would not need to be circuit changes involved.